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REPORT FOR ENGINEERS AUSTRALIA AUGMENTATION OF WATER SUPPLY TO THE ACT AND REGION (Electronic Version) PREPARED BY Ross A. McIntyre BE (Civil) FIEAust Reginald F. Goldfinch BCE, ME FIEAust, MAWA (Hon. Life) Kenneth Johnson BE, MIEAust., AmSCE. F. Charles Speldewinde MBE December 2003 The above photograph is reproduced by permission of The Canberra Times from the issue published in the Times on Wednesday, October 1, 2003. The caption to the photograph stated “Water cascades over the top of the Cotter Dam yesterday (Tuesday 30 September 2003) - but recovery of the catchment is expected to take 10 years”. Over the past three years the water flowing over the Cotter Dam included most of the water released from Corin and Bendora Reservoirs for environmental purposes in the 17km length of the Cotter River between Bendora Dam and the Cotter Reservoir. After overflowing at Cotter Dam this water flows down the Cotter River into the Murrumbidgee River and thence into Burrinjuck Reservoir. If this water had not been released for environmental purposes it would have been available as additional supply to the ACT during the current drought. This regime or water release has been in operation for about 2 1/2 years coinciding with drawdown of water reserves. (i) ACT WATER RESOURCES POSITION STATEMENT BY ENGINEERS AUSTRALIA, CANBERRA DIVISION With the height of summer weather ahead, Canberra’s reservoirs nearly half empty and Stage 3 water restrictions in place, there can be no doubt about the importance of a Water Resources Strategy for the ACT. Recognising the importance of this strategy, Engineers Australia (Canberra Division) commissioned a voluntary working group, comprising some of the most experienced water engineers in the country, to investigate and report to it on the ACT’s water resources. Drawing on this report Engineers Australia (Canberra Division) states the following as its position in regard to a strategy for the ACT’s water resources. (a) Canberra’s success as a national capital and a desired place to live has been and will be underpinned by the quality of its physical infrastructure and its engineering planning and design. Failure to ensure adequate water supply and sewerage facilities will render it difficult to retain existing industry and Commonwealth Government agencies and to attract new business to locate to Canberra. The importance of an adequate water supply is clearly recognised in the ACT Government’s recent Economic White Paper. (b) Canberra’s current water supply infrastructure was designed thirty or so years ago for a population of 450,000 and limited environmental flows, without recourse to water restrictions in the worst of droughts. (c) The introduction of the environmental flows as required by the 1998 Water Resources Act have resulted in a major drop in the security of the ACT’s water supply against restrictions, leading to the current low levels of reserves and associated restrictions. (d) The level of security of the water supply against restrictions is a matter for determination by the ACT community through its democratic institutions. As far as practical, such decision making should be informed, with the benefits, consequences and risks identified. (e) Whilst Engineers Australia (Canberra Division) is not aware of any economic assessment of the costs of the current Stage 3 water restrictions, it would expect that, were they to continue for the full summer, the total direct and indirect costs would be very significant. (f) With an increasing population and an expected reducing yield from catchments the already tight water supply situation will progressively further deteriorate in the absence of any intervention. (g) The water conservation measures, particularly innovative measures, proposed in the government’s “Draft Strategy for Water Resource Management” are supported. The saving of 25% per capita over the next 20 years, though a significant target to achieve, may do little more than keep pace with the increasing population and lower catchment yields, and then only for a time. (h) The environmental flows required under the Water Resources Act 1998 are very significant and have a major impact on the availability of water for consumption. The provision of these flows has significant direct financial costs (eg advancing the need for new infrastructure), indirect economic costs (eg the harm to some small businesses as a result of the water restrictions), environmental costs (eg degradation of the garden city concept for Canberra) and social costs (eg reduced availability of sporting (ii) facilities). The report also draws attention to the effect of the Stage 3 rationing on aged members of the community seeking to maintain their gardens with hand watering in hot conditions. The proposed review of the Environmental Flow Guidelines is therefore strongly supported. The question is also raised as to whether the criteria for the guidelines, eg the environmental benefit of the environmental flows, should be reassessed as part of the consideration of strategies for managing the ACT’s water resources so that adopted strategies represent an optimally balanced approach. (i) There are significant uncertainties in predicting urban expansion and development, climatic conditions, catchment runoff characteristics, vulnerability to bush fires, consumption levels and community expectations and hence in determining future water resource requirements and availability. (j) Major physical infrastructure requires a significant lead-time for investigation, planning, design, construction and commissioning before it becomes operational. In the case of major dams this could take 10 to 15 years. It is further noted that the major expenditure on infrastructure works occurs in the construction phase and not on the investigation, planning and design. (k) In light of the above it is concluded that it would be imprudent not to proceed expeditiously with the investigation, planning and design of new water resource infrastructure. (l) In consideration of possible future water resources infrastructure the following comments are made: (m) A regional approach should be considered as opposed to just solutions confined to within the ACT borders; (n) Both short term and longer-term measures regarding water supply infrastructure options should be considered. Options for consideration for selection should include (refer sections 4 and 5 of report): • Construction of a dam on the Naas River at Tennent; • Diversion of the Goodradigbee River to the Cotter River; • Diversion of the Upper Murrumbidgee River to the Upper Cotter River; • Construction of a dam on the lower Cotter River at Coree or enlargement or replacement of the existing Cotter Dam; • Pumped diversion of the Murrumbidgee River at Tharwa; • Diversion of treated effluent from LMWQCC to the Cotter River below Bendora Dam to meet environmental flow requirements downstream of this dam and so replace potable water currently being released; and • Diversion of the Naas-Gudgenby River system to Googong Reservoir. (o) Diversification of catchments from which the water supply is drawn provides additional security, eg vulnerability to local catchment effects such as bushfires is reduced. Hence in this regard the Tennent scheme has advantages over enlarging the existing Cotter Dam. (iii) (p) This Position Statement and the report by the Working Group focuses on the overall/aggregate water resource situation and accordingly has not specifically covered the impact of bushfires on the Cotter catchment. However, this impact further underlines the vulnerability of the ACT’s water resources and the benefits of a greater diversification of available catchments. (q) In undertaking the investigation, planning and design of new water resources infrastructure there is a need for adequate organisational structures and resources. The above Position Statement by Engineers Australia (Canberra Division) is commended to the ACT Government. The report by the working group is submitted for the government’s consideration. Whilst requested by the Division and drawn on by it in developing its position, the views and opinions in the report are, however, those of the authors and not necessarily those of Engineers Australia. The Canberra Division greatly appreciates the work done by the working group in the preparation of the report. Their effort and time, freely given, is an outstanding example of citizenship and social conscience - of which Engineers Australia and the people of Canberra can be proud. This Position Paper focuses on a central issue, the need to address the current vulnerability of the ACT’s water security. Engineers Australia recognises that determination of a suitable Water resources Strategy is a challenging and complex process and would like to further contribute to this through participation in discussion and, as applicable, subsequent submissions. Mike Evans President Canberra Division, Engineers Australia (iv) (v) (vi) AUGMENTATION OF WATER SUPPLY TO THE ACT AND REGION TABLE OF CONTENTS CANBERRA TIMES PHOTO i FORWARD/POSITION STATEMENT BY ENGINEERS AUSTRALIA CANBERRA DIVISION ii LETTER OF SUPPORT FOR REPORT BY PROFESSOR IAN WHITE v EXECUTIVE SUMMARY ix 1 INTRODUCTION 1 2 A BRIEF DESCRIPTION OF THE WATER SUPPLY SYSTEMS SERVING THE ACT AND REGION 1 3 THE CURRENT SITUATION REGARDING WATER SUPPLY TO THE ACT. 2 3.1 ANALYSIS OF RECORDS OF RELEASES OF WATER FROM RESERVOIRS FOR ENVIRONMENTAL PURPOSES. 2 3.2 COMMENT REGARDING THE EFFECTS OF ENVIRONMENTAL FLOWS 6 3.3 COMMENT REGARDING JOINT OPERATION OF THE RESERVOIRS OF THE COTTER AND QUEANBEYAN RIVERS 7 4 PROPOSALS FOR AUGMENTATION OF WATER SUPPLY TO THE ACT AND REGION. 7 4.1 PROPOSALS DEVELOPED BY SMHEA. 7 4.2 PROPOSALS DEVELOPED BY THE FORMER COMMONWEALTH DEPARTMENT OF WORKS. (CDW) 9 4.3 PROPOSALS FOR DEVELOPMENT OF A DAM AT THE TENNENT SITE. 9 4.4 ENLARGEMENT OF COTTER RESERVOIR 10 4.5 THE NEED FOR OPERATIONAL STUDIES. 11 5 PROPOSALS FOR AUGMENTATION OF WATER SUPPLY TO THE ACT AND REGION IN THE SHORT TERM 11 5.1 TEMPORARY CESSATION OF RELEASES FROM RESERVOIRS FOR ENVIRONMENTAL PURPOSES 12 5.2 REFURBISHMENT OF PUMPS IN THE COTTER PUMPING STATION. 12 5.3 THE GOODRADIGBEE RIVER DIVERSION PROPOSAL.

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